Flies and mosquitoes are usually common around most farm homes during the summer.
Flies are important household pests because most of them are a nuisance, just buzzing
around and being annoying, and because some of them are potential carriers of intestinal
diseases. Although most Manitoba mosquitoes are just an itchy annoyance, some can carry
encephalitis during outbreak years.
An understanding of fly and mosquito biology lets us
reduce their numbers on the farm to a tolerable level, often without the use of
insecticides. This publication outlines ways and means of identifying, preventing, and
controlling these pests in and around the farm home and yard, using an integrated pest
Section I of this report deals with flies. Section II deals with mosquitoes.
Adult flies have only one pair of wings. The second pair has evolved into tiny knobbed
structures used for balance and equilibrium. The larvae of flies are called maggots.
Maggots do not have legs and appear wormlike. Flies have a life cycle (shown in the
diagram opposite). Adult flies lay eggs on or close to the larval food, the eggs hatch
into larvae, and the larvae feed and develop into pupae. The pupa is inside a
leathery-brown pupal case, called a puparium. The pupa is a non-feeding stage from which
the adult fly eventually emerges.
The adult fly has the most distinguishable features and is the easiest of the stages to
identify. If you collect eggs, larvae or pupae, rearing it until it reaches the adult
stage will allow the easiest identification.\
A large number of different flies can be found on any farm over the summer
months but relatively few are both common and annoying. The first step in dealing with a
fly problem is to identify the kinds of flies present.
When the fly is identified,
effective methods and materials can be selected that focus on the prevention and control
of that species. Simple fly traps may be all that is needed in some cases. More
complicated approaches may be necessary in other situations.
Most of the common pest flies are easy to identify simply by comparing a specimen with
the illustrations provided below. Others are more non-descript and have to be keyed out by
a specialist using technical keys.
Integrated pest management system that anticipates and
prevents pests from reaching harmful levels by using all suitable techniques (e.g.,
natural enemies, cultural management, and the judicious use of pesticides).
Basic Biology of Common Flies
Once you know which flies are present on your farm, you can learn about their basic
biology. This will enable you to figure out the best means of controlling them and
preventing them from becoming a problem in the future.
|Black Blow Flies2
Adult black blow flies are dark green or blue-black on the thorax and abdomen and about
8-9 mm long.
Black blow flies are one of the most common flies associated with wound myiasis,
especially in livestock. In cases of myiasis, larvae sometimes cause a bloody discharge,
indicating a certain amount of destruction of living tissue.
The larvae normally feed in dead tissue, breeding in carcasses and wounds but they are
also common around household garbage cans. The larval stage takes 4-15 days. Growth from
egg to adult takes 8-15 days.
The adult life span can range from 45-68 days. They are more common in the spring and
fall and scarce in the summer. Cool weather favors development. These flies overwinter as
adults. Adults emerge for brief periods throughout the winter. In warmer climates,
breeding is continuous.
Most black flies are about 2-5 mm long, black or grey coloured, short legged, stout,
and the thorax is strongly convex, giving a humpbacked, gnat-like appearance.
Like mosquitoes, adult female black flies feed on blood and are often serious pests.
Black flies often occur in enormous numbers in the spring and early summer months, close
to clean, fast-moving rivers and streams where their larvae develop. They attack people,
cattle, deer, birds, and other animals. Livestock can die if bitten by large numbers of
On people, they crawl into sleeves, under neckbands, around boot tops and other
vulnerable places, especially favoring the head just beneath the rim of a hat. Bites can
cause swelling and numb soreness for many days. On cattle and horses, the ears seem to be
the favorite feeding location.
Flies lacerate the skin and suck blood. They have a strong anticoagulant in their
saliva that facilitates bleeding of the host. A lesion may form at the bite and the bitten
Adult black flies are migratory, commonly flying many miles from larval breeding sites.
Unlike mosquitoes, black flies are day-time feeders. During sunny, warm days, peak attacks
occur in mid-morning and then have a more intense phase in evening, ending at dusk.
However, biting greatly intensifies at the onset of storms and may persist all day when
overcast conditions occur.
|Blue Blow Flies4
The adult blue blow flies have a dull-coloured thorax and a shiny metallic blue-green
abdomen. They are about 8-9 mm long. The head is grey with large red eyes, black sides,
and reddish beard. The thorax is dark grey. The legs are dark grey to black and bristly.
The wings are clear.
Blue bottle flies breed almost exclusively in decaying animal matter. Female flies may
lay hundreds of eggs during their lifetimes. The eggs require 90% relative humidity to
hatch. If enough moisture is present, hatching occurs almost immediately.
The larvae grow rapidly and, when mature, often crawl many feet to pupate in drier
places, either in the soil or in crevices of buildings. New adults emerge in 2-3 weeks.
They can have several generations per season. They often overwinter in buildings.
Cluster flies closely resemble house flies, but
they are usually larger (9.5-12.5 mm) and have a yellowish sheen on
the thorax. With a mostly black body, their thoracic hairs are
short, curly, and yellow to golden. They have tufts of crinkly
yellow-orange hairs where their wings attach to the thorax. Older
specimens may have some of the yellow thoracic hairs rubbed off. The
wings often overlap at their tips when the fly is resting.
larvae are parasites of earthworms and breed outdoors in
lawns and fields during the spring and summer. Earthworms
are usually most abundant around places where manure has
been piled or stored and are common in grassy areas where
the soil is moist.
The large numbers of adults that emerge in
late summer and early fall seek protected places to spend the
winter. Often, as with face flies, this site is a structure. Inside
a structure, the flies tend to "cluster" in large numbers at windows
or on ceilings or other high places.
They often occur within the walls, attics and
basements of homes. Window screens alone offer no protection from
these flies because they crawl into the home through small openings
in the walls of the building.
Their habits inside a home are similar to those
described below for face flies. Both face flies and cluster flies
may be attracted to the same structure year after year. Cluster
flies are also bothersome in the spring when they try to escape from
When crushed, they leave a greasy spot on
upholstery, carpets, and painted surfaces and give off an odour like
Tabanidae include both deer flies and horse flies (see below). Deer flies are smaller
than horse flies (10-13 mm long). Their wings are tinted smoky brown or have dark
patterns. Their thorax is greenish-yellow with dark stripes. The eyes touch each other on
the top of the head in males and are separated in the females.
Deer flies are often serious pests of livestock and
They are often seen around swamps, marshes, and ponds. The males are found on flowers
and feed on nectar and pollen. The females are usually seen circling your head.
The larvae of deer flies are aquatic and are mostly found in shallow water or moist
soil along the edges of ponds, dug-outs, small streams, and cattail areas of some ditches.
They feed on decaying organic matter.
There are many kinds of dung flies but the most striking is the yellow dung fly. This
bright yellow, hairy fly is about 9 mm in length. It has dark bristles on long slender
Many kinds of dung flies breed in cow, horse, pig,
and sheep dung. The larvae of some species live in decaying plant material and can be very
abundant in rotting vegetation and mud along shorelines. Most of the small black flies
that fly up if you disturb a fresh cow pat are dung flies. The common yellow dung fly is a
typical example of this family and, although their larva feed on the dung, the adults are
predatory and feed on other flies which have come to the dung to feed.
Swarms of the furry, golden males collect on steaming, fresh cowpats. The arrival of
females is greeted with flurry of activity and mating pairs can be seen. The eggs are laid
in dung. The females prefer fresh cowpats because older ones form a crust and it becomes
very difficult for egg laying. As the pat gets older, therefore, fewer and fewer females
The larvae feed in the dung, eating organic matter and other smaller fly larvae. When
they devour the larvae of common stable flies, the larvae destroy a pest that causes
endless aggravation for cattle. The larvae of some species are found in damp soil where
they prey on small invertebrates.
Although dung flies may resemble bees in appearance, they leave us and our animals
alone. Considered beneficial insects, they are harmless to people, pets, and livestock.
These small (6-8 mm long), non-biting flies are greyish-brown in colour with 4 dark
stripes on the thorax and a grey-black patterned abdomen. In the female, the abdomen has
little yellow or orange on the sides but, in the male, the sides of are yellowish-orange
The eyes of the female are surrounded by a silvery stripe; the male's eyes almost touch
in the center. The mouthparts of the face fly are fleshy and blunt and do not protrude
straight from the head like a bayonet, as do those of the horn fly and stable fly.
Face flies superficially look like house flies but
they lay their eggs only on fresh cattle manure in fields. The life cycle takes about 2
weeks. The larvae develop within the dung and pupate in the surrounding soil.
Unlike the house fly, face flies are pests of cattle in pastures during the warm
months. The adult female flies tend to feed on secretions from the eyes, nostrils, and
mouths of pastured cattle, causing extreme annoyance and allowing for the transmission of
pinkeye and other eye diseases.
By contrast, male face flies feed only on nectar and dung. They spend much of their
time resting on branches and fences and attempting to catch and copulate with female flies
as they move about.
Face flies are strong, robust fliers that can travel several miles. Unlike house flies,
face flies do not enter darkened barns or stables during the summer months. However, in
the fall, they will enter farm homes and other buildings and overwinter indoors near
pastures or where cattle are kept. During warmer days in the early spring, some face flies
may come out of their hiding places in the attic and walls and appear on south-facing
Adult flesh flies are greyish with 3 black stripes running the length of the top
surface of the thorax (just behind the head). They have a light and dark checkerboard
pattern on the abdomen and are about 10-13 mm long.
Flesh flies are similar to blow flies in their
biology. Most flesh flies near the home are attracted to odours of decay.
They breed in excrement, decaying vegetation, and animal flesh or meat. The female
deposits live larvae on fresh animal carcasses and on dead snails and large insects.
Blow fly larvae and grasshopper nymphs are common hosts of flesh flies. There are
recorded cases where females have deposited larvae into open wounds of animals, including
humans, hence their names as flesh flies. The adult flies do not bite but feed on a wide
range of liquid substances.
Most larvae infest wounds, carrion, or excrement. The larvae of some species of flesh
flies are beneficial in that they prey on eggs, nymphs, or larvae of more harmful insects.
Green Bottle Flies10
The adult green bottle blow flies are shiny metallic green to bronze. Medium-sized,
these stout flies are 7-14 mm long.
The thorax has 3 cross-grooves and black bristle-like hairs. The antennae and legs are
black. The wings are clear with light brown veins.
Female green bottle flies lay up to 180 eggs on
carrion, dead fish, manure, unprotected wounds, or garbage. The larvae attain full size in
2-10 days, drop to the soil, and burrow shallowly before pupating. There are up to 8
generations a year, the last overwintering as larvae in the soil.
The green bottle fly is not as attracted to the smell of fresh meat as is the blue
bottle fly. It is also less likely to enter homes. It is often found near dog feces,
manure, and garbage cans.
Adult horn flies are slender, 3.5-5 mm long and are about 1/2 the size of a typical
housefly. They are charcoal gray in colour, with 2 dark stripes on the thorax, and a few
diffuse spots on the top of the abdomen. They have an extended, piercing proboscis and
Horn fly adults typically occur on cattle farms but
they may also attack sheep, goats, horses, mules and dogs on any farm. The flies spend
most of their life on the host animal, usually congregating on the back and shoulders.
During very hot or rainy weather, the flies move to the underside of the belly. Both sexes
bite intermittently and may feed up to 20-40 times per day.
Large numbers of flies (more than 500 per animal) cause lower weight gains and milk
yields. Animals become so annoyed that they may injure themselves while attempting to
dislodge the flies. They do not bite people. Like stable flies, the mouthparts of horn
flies are extended forwards from the head as a piercing proboscis.
Females require blood meals for egg production and can lay several hundred eggs during
their lifespan. They leave the host briefly to lay eggs on very fresh, undisturbed cattle
manure. The larvae are yellowish-white maggots. They complete their development in the pat
within 1-2 weeks. The entire life cycle is completed within 2-4 weeks. Horn flies
overwinter as puparia beneath cow pats and emerge the next spring as adults.
Horse flies are like deer flies but much larger and heavier-bodied (14-19 mm long).
Their wings are clear and their thorax is usually brownish-grey striped.The abdomen may be
orange and black patterned or similar to the colouration of the thorax.
As with deer flies, you may encounter these flies
on farms nearby streams, dugouts, ponds, and lakes, where their larvae breed in decaying
organic matter. Like the deer fly, the female horse flies lay their eggs in masses on
vegetation overhanging water. The larvae are omnivorous, feeding on organic debris, other
insects, tiny crustaceans, snails, earthworms, and other small organisms. Development from
egg to adult requires 70 days to 2 years, depending on the species.
Female horse flies cut through the skin with knifelike mouthparts. They then feed on
the blood that pools around the wound. The wound continues to bleed after the fly leaves
and often attracts face flies.
On dairies and livestock farms, large numbers of these flies can cause extreme
annoyance and fatigue, blood loss, reduced milk production, and reduced weight gain. Some
species have also been implicated in the transmission of tularemia, anthrax, anaplasmosis,
House flies are 4-8 mm in length and black with 4 dark stripes on thorax. The abdomen
is greyish or yellowish at the sides and has a dark stripe down the middle. These flies
have fleshy mouthparts. The eyes are reddish and are well separated in male. The eyes have
a golden stripe around the outer edge.
The legs are hairy with adhesive pads and sharp claws. The wings are clear and are held
level and straight back.
The house fly is probably the most common fly found
on Manitoba farms. Most flies caught in houses are house flies. The house fly causes
complaints on farms near sanitary landfills, poultry farms, dairies, or other sources of
rotting organic matter of plant or animal origin that attract egg-laying females.
House flies have been implicated in the spread of over 30 bacterial and protozoan
diseases. Fortunately, house flies do not transmit many of these diseases with great
frequency. Because they can transmit many serious diseases, house flies are considered to
be a greater threat to human health than most other insects.
The female lays her batch of eggs (75-150 eggs) on wet, decaying organic matter lying
in the open (e.g., on wet garbage, animal manure, spilled feed, bedding, decaying fruit,
compost piles, rotting plant debris, landfills). She can lay 4-6 batches in a lifetime.
These eggs usually hatch within 24 hours into tiny, creamy-white maggots that feed in
the waste. Mature maggots migrate away from their food sources in search of suitable sites
for pupation. They change into the pupal stage from which the adult flies emerge. It takes
about 2 weeks for a fly to go from the egg to adult stage. Males live for 2 weeks and
females up to 3.5 weeks.
Adults feed on a wide range of materials, including feces, garbage, fresh and decaying
fruit, and most human food. Adult flies are very strong fliers.
Stable flies resemble house flies with their dull appearance and their 4 dark stripes
on the upper body. These flies are 5-8 mm long. The abdomen has dark spots.
"Checkerboard" markings are obvious on the underside of the abdomen. Stable
flies have a needle like, stiff, piercing mouthpart that is folded below their head.
Both sexes feed on the blood of warm-blooded
animals (including people, dogs, and horses). They are often a pest on farms that have
cattle in pastures and feedlots. They often bite through clothing, especially on the
ankles. Dogs that are kept outdoors can be tormented and severely bitten. Adults do not
feed at night.
Females lay 40-80 eggs per batch and 10-12 batches in a lifetime. Larvae can develop in
urine-soaked straw, chicken manure, compost piles, wet hay bales, and grass clippings.
The stable fly also breeds in vegetation strewn along the shorelines of lakes and bays
and in accumulations of wet grass clippings from yards and golf courses.
Maggots burrow into the breeding material, following moisture inward as the substrate
dries. Under favorable conditions, the entire egg to adult life cycle is from 21-25 days.
This can be as long as 78 days in unfavorable conditions or in cool climates. Before
pupation, the mature larva crawls to drier parts of the medium. Stable flies overwinter as
larvae or pupae.
Stable flies can move great distances. This often occurs when they are picked up by
weather fronts and carried aloft for several hundred miles. Uninfested areas thus can
become heavily infested almost overnight.
Fly Prevention and
Flies can be controlled without using insecticides, except when large numbers of adult
flies have already inundated a farm site. Fly control is more effective in the long-term
if sanitation and prevention are the basis of the control program. The non-chemical
alternatives include the use of special fly traps, physical control, and exclusion.
Prevention Through Sanitation
It sounds simple but sanitation is still the most effective and important way to
control flies. All outside trash areas must be kept clean. Garbage should be drained and
wrapped in plastic bags before being placed in trash receptacles outdoors.
Use garbage cans with tight fitting lids, lined inside with plastic
bags. By placing garbage in secure plastic bags, odours will be reduced, therefore
attracting fewer egg-laying flies. Periodically, food residues should be washed from
garbage containers. The best time to clean garbage cans is in the early summer. Locate the
garbage cans as far away from the farm house or building as possible. Dispose of garbage
weekly at a regular landfill or by incineration.
Eliminate potential breeding materials (e.g.,
rotting straw bales, loose straw, or mulch, leaves, manure, garbage, and animal
excrement). Compost piles can be covered with black plastic that will heat the organic
matter, destroying fly larvae. Wooden compost boxes can be painted dark-brown or green to
blend in and absorb heat.
Household and livestock-related garbage, dumped at
the local landfill, can quickly generate large numbers of flies, especially when the
garbage already contains fly eggs, larvae, or pupae. Landfill workers must be aware of
this possibility and compact and cover such garbage at least twice weekly.
Occasionally, wet farm garbage (e.g., wet, spoiled grain; wet, waste from calf pens)
that is brought to the landfill is loaded with fly maggots and pupae. Landfill workers
should be alert to this and immediately compact and cover such material. Thousands of
adult flies may emerge from such garbage within a few hours.
Avoid moist pet foods left outdoors for several days. Remove fallen, fermenting, or
over-ripe fruits from the ground. Any potential breeding material should be spread thinly
in the field and allowed to dry to prevent fly development.
Dispose of animal carcasses (including livestock,
pigs, and poultry). Collected carcasses must be removed quickly during the summer.
Otherwise, they will quickly become "fly factories" within 24-48 hours. Dead
livestock can be quickly and conveniently removed by calling Rothsay (Maple Leaf Foods) in
Winnipeg at (204) 233-7347.
Road kills are another source of flies. A small animal (e.g., dead cat, ground
squirrel, tree squirrel, rabbit, or porcupine) can easily produce more than a thousand
blow flies if left by the side of the road. Dead deer, left to rot in a ditch, can yield
tens of thousands of flies. You should report such problems to Manitoba Highways and
ensure that the carcass is promptly removed.
Prevention Through Exclusion
Flies seem to be able to find their way into homes, garages, shops, and bins through
the smallest of overlooked entrances. Even when all windows have good screens, when all
doors have screened storm doors, and when all known cracks and crevices have been filled
with caulking, the odd fly seems to get inside the home. Just everyday coming and going
through the back door allows agile flies to get inside the home.
Sometimes, they are able to find their way into attics and, from there, into the home
proper through various vents and electrical outlets. Nevertheless, careful attention to
blocking all of their normal entrances to a building should reduce their numbers inside to
a more tolerable level.
Screen doors should open outward and have fitted springs for tight closing. Because
flies are quick at entering opened doors, a double set of doors is best where adult fly
populations are really heavy.
Solid animal wastes (e.g., those produced in buildings, corrals, or pens) can be
collected and composted until such time as they can be spread thinly on fields. Clean
cattle pens, drainage areas, loafing sheds, stalls, feeding aprons, spilled feed, pet
droppings, and other decaying organic matter at 10-day intervals to minimize fly breeding.
Liquid wastes can be pumped from holding pits, in the spring or fall, to be spread over
or injected into fields.
The right time to spread manure is in the spring, as soon as the fields are dry enough
to travel on with spreading equipment. In the fall, after harvest is complete, is the
second best time. There is little chance of any fly larvae completing their development
During both periods, weather conditions are usually cool with overnight frosts,
reducing both nutrient loss and odour problems, especially when the manure is immediately
incorporated into the soil.
Control With Fly Swatters and Tapes
A simple fly swatter or folded newspaper is effective indoors against a few individual
flies. Rolls of sticky fly paper are available from most hardware stores. Use the tapes on
porches and in garages and storage sheds where aesthetics are not important.
Control With Vacuuming
Flies found inside in the fall may also be removed with a vacuum. Because flies are
drawn to light, attract them to a bright window in an otherwise darkened room, making it
easier to vacuum them. This method is especially useful in cluster fly control.
Control With Electric Light Traps
Electric light traps are available commercially to control house flies in homes. Some
are designed to be unobtrusive, blending in with the décor. They are ineffective
outdoors. For farm buildings, including livestock facilities, utilitarian models are
available in a wide range of sizes. These types of traps are generally fairly expensive
but worthwhile where sanitation is a vital concern.
Control with Baited Jug Traps
Some jug, bag, and jar traps use bait and water to attract and capture flies. These are
especially effective against the various kinds of blow flies. Several types and brands are
available but one of the most popular is the Fly Terminator, a 4 L trap that uses an
attractant in water (and the odour of dead flies) to draw in the flies. It has an
effective attracting radius of about 35-50 m. The larger size is available from local feed
mills (e.g., Manitou Feed-Rite). The smaller disposable traps are usually available from
most local True Valu and Co-op lumber and hardware stores.
Trap placement is important. If the farm yard has a
small or moderate fly problem, traps placed close to the home can attract flies from all
over the area and make the problem worse.
It is better to set the traps close to fly breeding sites with any prevailing breeze
blowing from the trap toward the breeding area. Place traps well away from outdoor areas
that are used for eating or recreation.
Control With Sticky Fly Traps
Old-fashioned, sticky fly coils, some with and some without fly attractants, can be
hung in garages, screened decks or porches where the occasional fly gets in through an
open screen door or pet entrance.
Considered by most people to be too unsightly for
use inside the modern farm home, the fact remains that they are relatively cheap and very
effective fly catchers. They seem to be most effective against house flies because these
flies tend to rest on hanging vertical surfaces more than most other kinds of flies.
Control With Horse Fly Traps
The Manitoba or black ball horse fly trap is essentially a pyramid-shaped tent raised
about three feet off the ground with a large, black-painted beach ball hanging underneath.
For some reason, horse flies are attracted to a large, black ball. When they discover the
ball is not a source of food, they fly up and away. They are then caught within the tent
and continue to crawl or fly upwards. At the top is a plastic jar that looks and acts like
a minnow trap to capture the horse flies. Some people just cover the heat-absorbing ball
with Tanglefoot and hang it so the sticky ball cannot contact anything. Where horse flies
are a severe problem, several traps may be needed to significantly reduce biting.
Commercial versions, like the one shown below, are available.15
Horse and deer flies use trees and bushes for
resting sites, and tend to fly along the edges of woods. Placing the trap in the middle of
narrowed areas between buildings will catch flies flying across those 'shortcuts".
Other good areas to set up the trap are next to dug-outs, shelterbelts, and livestock pens
or barns. Many traps have been design to catch specific groups of flies.
Control Using Biocontrol Agents
A fly's natural enemies include predators, parasites, and pathogens. Although some of
these organisms are commercially available from the U.S.A., special permits must be
obtained from Agriculture Canada to import most of them into Canada. Sometimes, Canadian
sources advertise in farm weekly newspapers. Some success has been reported in using fly
parasites, chickens, and ducks for fly control on livestock farms.
Because widespread spraying with insecticides for fly control kills natural enemies,
every effort should be made to prevent fly problems and, if they still occur, to use
non-chemical methods of fly control.
Personal Protection From Biting Flies
Biting fly control (including black flies, stable flies, and mosquitoes) is difficult
due to the migratory adult stage and their extensive breeding habitats. In terms of
personal protection, choice of clothing can be important. Biting flies are highly
attracted to dark colours, so wear light coloured clothing. A hat, long-sleeved shirts,
and pants are also important. Proper clothing, plus the use of insect repellent on exposed
skin, will minimize bites from these insects.
Chemical Fly Control
Total reliance on insecticide applications in and around the house often results in
failure to produce long-term control results. Constant effort must be made to eliminate
and dry out potential fly breeding sites. At times, insecticides may be helpful in
reducing heavy nuisance fly populations.
Insecticides for Fly Control Outside the Home
Treat outdoor surfaces where flies rest, especially around doors, windows, screens,
gables, garbage cans and trash piles with a residual spray of a Health Canada-approved,
There are many insecticide formulations labelled for fly control. Some emulsifiable
concentrate formulations of dichlorvos, dimethoate, methoxychlor, and permethrin can be
used outside as residual sprays. See the opposite table for other formulations. Remember,
before using any insecticide, always read and follow label directions and safety
precautions (the label is the law).
In some cases, heavy fly populations are best controlled by a licensed pesticide
applicator or professional pest control firm. Homeowners often do not have the experience,
cannot obtain certain insecticides or do not have the proper equipment needed to perform
the control job effectively.16
Some of the more commonly used insecticides, available for fly control in the yard and
on the outside of the buildings, are listed in the table below. In addition, there are
dozens of different ready-to-use sprays available at local stores.
Whichever product is purchased, ensure that it can be used where flies are a problem on
your farm. Something that might be appropriate in a dairy barn might not be suitable for
use around the home. Carefully follow all label directions and precautions.
Suspend 1 insect strip per 30 m3 of air space.
Mix wet or dry bait using sugar as an
attractant. Follow label instructions.
Scatter 1% bait using 125 g bait per 100 m2.
Premium Golden Malrin
Scatter 125 g of 1% bait per 50-100 m2
to areas where flies congregate.
Residual Wall Sprays
Use 0.5% spray.
Mix 2.5 L 4E per 100 L water.
Apply 5 L
mixture/50-100 m2 .
Mix 160 g 80% SP in 100 L water and apply 5 L
mixture per 50 m2 .
Use 3 mL Dibrom in 1 L water and apply as a
Apply ready-to-use mixtures as a
mist or space spray or from automatic dispensers.
Apply by aircraft or mist blower
according to label directions.
Insecticides for Fly Control Inside the Home
To kill the annoying flies that buzz about rooms, you can use a synergized pyrethrins
spray or aerosol. You will obtain best results with pyrethrins if the room is closed and
the spray or aerosol is misted into the air. Other products (containing allethrin,
permethrin, phenothrin, resmethrin, sumithrin or tetramethrin) are also available. All of
these products are "quick kill" insecticides and have little or no residual
After using a spray indoors, leave the room and wait until the odour of the
insecticide disappears before using the room again.
Cluster flies, face flies and blow
flies are difficult to control once they have gained access to homes because they
hibernate in wall voids and other inaccessible places. If there is a severe infestation,
you could use a 2- or 3-gallon compressed air sprayer to apply a 3% Malathion residual
spray to surfaces in attics, basements, closets, store rooms, and other areas where the
You could also inject diazinon or bendiocarb dust into window pulley
openings and, wherever possible, into wall voids and other confined spaces where the flies
may be hibernating.
Resin strips containing dichlorvos may be hung in areas containing
these flies if there is little or no air movement. Use one 10-inch strip per 1,000 cubic
feet of space.
These strips are effective up to about three months but only if they
are placed in the same "chamber" as the flies. Note that piles of dead flies
left in the attic can sometimes lead to secondary infestations of carpet or larder beetles
Rotate Insecticide Use
Flies are becoming increasingly difficult to control with many insecticides, especially
inside farm buildings. The interiors of such buildings are like small islands. A few flies
unaffected by a given insecticide quickly generate a whole population of flies resistant
to that insecticide or, in some cases, to the class of insecticides to which the product
If flies are a perennial problem around a farm-site, it is good practice to rotate
insecticide use. For example, with cluster flies, the exterior of a building might be
treated first with a synthetic pyrethroid (e.g., permethrin) and later with an
organophosphate insecticide (e.g., dichlorvos).
II - Mosquito Prevention
Mosquitoes are actually small, slender flies that have long thin legs and
a long and sharp proboscis. The males have feathery antennae and the females have sparsely
haired antennae. Only the females are blood feeders. The males feed on nectar. Of the
human diseases that are known to be transmitted by mosquitoes, western encephalitis is the
most important in Manitoba.
The larvae are aquatic and occur in small ponds, pools,
ditches, tree holes, and in water-filled artificial containers. The larvae feed on algae
and organic debris.
The adults are common near water and are usually most active at sunset,
during the night, or when calm, cloudy, humid conditions prevail. The life cycle of the
mosquito is similar to that of the fly, except that the non-adult stages are aquatic.
are laid on the surface of the water or the edges of dried up or stagnant pools of water.
The larvae go through four actively feeding larval instars before turning into non-feeding
pupae. The adult emerges from the pupa after 2-3 days. In Manitoba, larvae require between
5 days and 4 weeks to mature, depending on water temperature and species.
The fresh adults emerge a few days later. Under ideal conditions, mosquitoes can go
from eggs to adults in 6 or 7 days.
A few days after
emerging, adult females are ready to feed and mate. A blood meal is usually required
before females can lay eggs and repeat the life cycle. Each female lays batches of about
100 eggs. The eggs of many of our nuisance species are drought resistant and can remain
viable for several years. Some mosquitoes produce several generations per year but most
complete only one or two. Some mosquitoes pass the winter as fertilized adults whereas
others overwinter as eggs or larvae.
How to Reduce Farm Mosquitoes
fish; remove excess vegetation
off cover; maintain water quality at all times
with sand or mortar
when not in use, turn upside down, or cover so
mosquitoes cannot lay eggs
water; store in an inverted position; dispose of; or
water at least once a week
by draining; fill in low areas
fish or change the water weekly
fall to remove leaf debris
over-irrigation; drain standing water
top or treat with detergent weekly
drainage holes, drain any water present; keep
drain plug and tilt when storing
Store on a
rack, upside down
recycling centre; drill drainage holes in tires used
there are no depressions that collect water
grass and weeds to minimize mosquitoes using them as
Personal protection may be achieved with clothing and repellents.
Mosquitoes are highly attracted to dark colors, so wear light colored clothing. A hat,
long-sleeved shirt, and pants are also important.17 Proper
clothing, plus the use of an insect repellent containing DEET on exposed skin, will
minimize bites from these insects.
Just as window and door screens are a necessity for flies, the same holds true for
mosquitoes. Keep all screens in place and in good repair.
Controlling Larval Mosquitoes
Although the best way to control mosquito larvae is
through draining and filling low areas that form stagnant pools of water and by ensuring
water is not allowed to collect in artificial containers, it may sometimes be necessary to
treat larval breeding sites with an approved mosquito larvicide.
Only a few products are available for domestic use. The most common product used on the
farm is Malathion 50EC, widely available at most local chemical sales outlets. It can be
used as directed on the label to treat mosquito-breeding sites wholly confined to your
farm property. A more environmentally acceptable product is BTK, a bacterial formulation
that is specific to mosquitoes. Products available to the farmer include domestic
formulations of Aquabac 200G18 and Vectobac 200G19.
Controlling Adult Mosquitoes With Insecticides
Insecticides for mosquito control in and around the
house can only give temporary relief. A constant effort must be made to eliminate
potential larval mosquito breeding sites. But, even if you eliminate all possible breeding
sites on your personal property, mosquitoes from other areas will still fly to your part
of the world. In such cases, insecticides may provide some relief.
Controlling Mosquitoes Indoors
If you have an indoor mosquito problem, you can use a space spray to kill
them. This can be done with a hand-held, synergized pyrethrin aerosol spray. Other
products (containing allethrin, permethrin, phenothrin, resmethrin, sumithrin or
tetramethrin) are also available. All of these products are "quick kill"
insecticides and have little or no residual action.
using a spray indoors, follow all label precautions and be aware that some people, pets,
and plants may be sensitive to the spray. After spraying, leave the room and wait until
the odour of the insecticide disappears before using the room again.
Controlling Mosquitoes Outdoors
Mosquitoes can be controlled
outdoors with either the old-fashioned thermal fogger
(above) or the new, more effective, cold foggers (bottom).
Canadian sources of this equipment include Pestalto
Environmental Products, Viceroy Distributors20, and M.K.
Rittenhouse & Sons.21
Foggers give quick knockdown and
kill but have no residual effect. Malathion 50EC can be used in thermal foggers.
Several products (including those containing pyrethrin, resmethrin, or malathion) are
available for cold foggers. Your local chemical sales outlet can order in products for
For greatest effectiveness with foggers, treat the area in the evening when mosquitoes
are most active and when weather conditions are most suitable (i.e., low winds, warm
temperatures, higher humidities).
Residual spraying is the other option. In many cases, you
will find mosquitoes resting on or in certain shrubs, small trees, ground cover and other
such vegetation. Residual sprays are an excellent choice to use in this case, giving
several days of control. Products available include Malathion 50 EC, Methoxychlor 240 EC,
and Permethrin 500 EC.
Residual sprays leave a long-lasting residual deposit on the
vegetation. When treating for mosquitoes, lightly spray top and bottom surfaces of
foliage. The best time to treat vegetation is early morning or late evening when wind
speeds are less than 10 km/h.
This report is a Covering New Ground Project,
sponsored by Manitoba Agriculture and Food. The author, Dr. Roy Ellis (Prairie Pest
Dr. T. Galloway and Dr. R. Roughley of the University of Manitoba Entomology Department, R. Gadawski
of the City of Winnipeg Insect Control Branch, and L. Manaigre, J. Gavloski
and B. Elliott of Manitoba Agriculture and Food Soils and Crops Branch for providing
specimens, technical information, and/or advice. All drawings are copyright of the author.
This report contains advice and insecticide
recommendations that are subject to change at any time. These recommendations are provided
only as a guide. It is always the insecticide user's legal responsibility to read and
follow all current label mixing directions and precautions for the specific insecticide
being used. Because of constantly changing product labels and product registrations, some
of the recommendations that are given in this report may no longer be legal by the time
you read them. If any information in these recommendations disagrees with the label, the
recommendation herein must be disregarded. No endorsement is intended for products
mentioned, nor is criticism meant for products not mentioned. The author and the
sponsoring organization assume no liability resulting from the use of these
Suggested Citation: Ellis, R.A., 2002. Mosquito and
Fly Prevention and Control on Manitoba Farms. Manitoba Agriculture, Food
and Rural Initiatives, Soils and
Crops Branch, Unpublished Report, 16 p.
2 Family: Calliphoridae;
Species: Phormia regina
3 Family: Simuliidae; ex, Simulium sp.
4 Family: Calliphoridae; Species: Calliphora vomitoria and
5 Family: Calliphoridae; Species: Pollenia rudis
6 Family: Tabanidae; Species: ex, Chrysops species
7 Family: Scathophagidae; Species: Scathophaga stercoraria
8 Family: Muscidae; Species: Musca autumnalis
9 Family: Sarcophagidae; Species: Arachnidomyia (=Sarcophaga)
10 Family: Calliphoridae; Species: ex, Phaenicia sericata,
11 Family: Muscidae; Species: Haematobia irritans
12 Family: Tabanidae; Species: ex, Tabanus
13 Family: Muscidae; Species: Musca domestica
14 Family: Muscidae; Species: Stomoxys calcitrans
15More information about the commercial trap is available:
Toll-free at 1-888-685-2244 or by writing to Newman Enterprises, 4552 Poygan
Avenue, Omro, WI 54963
16 For treating buildings, call a pest control
operator who is licensed in Manitoba (ex, Poulins Exterminators in Winnipeg at
204-233-2500 or 1-888-768-5467; PCO Pest Control in Winnipeg at 1-800-726-7378; or Swat
Team Pest Services in Winnipeg at 204-925-7928). For treating larger yards, call
a local aerial applicator
17 See Gempler's
catalogue for special bug jackets. Call 1-800-382-8473 or write Gempler's, 100 Countryside
Drive, PO Box 270, Belleville, WI 53508 USA to request a catalogue
18 Canadian Bio Services, 768 4th Street CP 32,
Shawinigan, Quebec G9N 6T8, Phone: 819-536-0075; or 1-866-648-7773
19 GDG Environnement Ltd., 375 Vachon, Cap-de-la-Madeleine, Quebec
G8T 8P6, Phone: 819-373-3097 or Even-Spray and Chemicals Ltd. Inc., Bay 2-851 Lagimodiere
Boulevard, Winnipeg, Manitoba R2J 3K4, Phone: 204-237-9095
Distributors, 65 St. Annes Road, Winnipeg, Manitoba R2M 2Y4
21 M.K. Rittenhouse & Sons Ltd., RR 3, 1402 4th Avenue, St. Catharines,
Ontario L2R 6P9